Automatic efficient irrigation threshold setting

ABSTRACT

A method and system for monitoring the dynamic response of soil moisture and setting a threshold in relation to the field capacity of a soil area is disclosed herein. By measuring the dynamic response of soil moisture under wet soil conditions, one can determine a practical field capacity for the soil, in-situ, based solely on the soil moisture sensor output. Essentially, by looking at how the soil moisture level varies with time one can determine the field capacity.

CROSS REFERENCE TO RELATED APPLICATION

The Present Application claims priority to U.S. Provisional PatentApplication No. 61/553,165, filed on Oct. 29, 2011, and U.S. ProvisionalPatent Application No. 61/553,238 filed on Oct. 30, 2011, and thepresent application is a continuation-in-part application of U.S. patentapplication Ser. No. 13/017,538, filed on Jan. 31, 2011, which claimspriority to U.S. Provisional Patent Application No. 61/300,028, filed onFeb. 1, 2010, all of which are hereby incorporated by reference in theirentireties.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is relates to an irrigation system. Morespecifically, the present invention relates to an irrigation systemdesigned to reduce water usage.

2. Description of the Related Art

The prior art discusses other irrigation systems and methods.

In attempting to efficiently apply irrigation water, a critical problemis setting watering thresholds to an appropriate level that achieves twogoals—minimizing water usage, and maintaining plant health. In general,it has been found that these two goals can be met by setting the watertarget to a percentage of the field capacity (generally 70% to 80%). Inorder to determine the field capacity (moisture content of a particularsoil at which water freely drains under gravity) one can take a soilsample for every type of soil where a soil moisture sensor is installed.This process is time consuming, expensive, and in practice, notparticularly accurate.

The Present Invention seeks to resolve the problems of the prior art.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a method for automatic irrigationthreshold setting. The method includes measuring a dynamic response ofsoil moisture of a soil area under a fully saturated environment andsetting a threshold for the soil area based on the measurements of thedynamic response.

One aspect of the present invention utilizes a smart irrigationcontroller, which is coupled to a set of sensors. The smart controllercontrols irrigation and monitors dynamic moisture responses. Thecontroller monitors an increase in soil moisture in response to a periodof time of active irrigation in order to determine irrigationefficiency, as well as to determine runoff and run times required toaccount for soil moisture deficits during irrigation events. Thecontroller also derives at least one of a set of soil/landscapeproperties, which includes field capacity, water infiltration rates,presence of thick organic surface areas (thatch); and produces at leastone recommendation for management practices comprising aeration, thatchremoval, soil amendment; and detects at least one of several irrigationsystem deficiencies, such as broken sprinkler heads, drip lines, andpoor spatial coverage.

Monitoring the dynamic response of soil moisture is preferably over apredetermined time period.

The soil area is preferably a residential lawn. Optionally, the soilarea is a golf course, a farm, a football field, all irrigatedrecreational surfaces, agricultural operations, gardens, landfill caps,or other land areas being restored to plant covering.

Another aspect of the present invention is a threshold setting that is70% to 80% of the field capacity of the soil area. The threshold iscapable of changing to a percentage of field capacity that may bedependent upon additional factors, such as, time to next scheduledevent, or available irrigation water, plant type, slope, etc.

Yet another aspect of the present invention is a threshold setting thatis set to optimize water efficiency, plant growth and plant health, tominimize runoff, and to minimize contamination to groundwater.

Yet another aspect of the present invention is a method whereby alladaptive algorithm operations are consistent with watering restrictionsthat are imposed by regulatory authorities or imposed by the end user toprohibit watering during certain times.

Yet another aspect of the present invention is a method that relies onexternal data provided by a communication capability to modifyirrigation practices to reflect at least one of local emergencies,current weather making irrigation inefficient such as high winds ortemperatures, or other factors.

By measuring the dynamic response of soil moisture under wet soilconditions, one can determine a practical field capacity for the soil,in-situ, based solely on the soil moisture sensor output. Essentially,by looking at how the soil moisture level varies with time one candetermine the field capacity. When the soil is wetted above fieldcapacity, its moisture content will fall fairly quickly initially to apoint where field capacity is reached. After this point, moisture levelswill continue to decrease but at a much slower rate reflectingevapotranspiration from the soil. By using sensor data, an uC, andappropriate algorithms, one can develop procedures for automaticallysetting determining field capacity and setting thresholds. Inresidential, agriculture, or in sports/turf markets the presentinvention sets this as either a “set threshold” mode or a continuouslyadapting mode adaptive.

In a set threshold mode, shortly after installing the sensors, we wouldput our central irrigation controller into a set threshold mode. Wewould then fully saturate the soil around the sensors either manually orthrough turning on irrigation. We would then monitor the dynamicresponse of soil moisture over some period of time (probably around afew hours to a few days) and determine field capacity. These valueswould then be used to set the thresholds.

In an adaptive mode, the system would continuously be monitoring thedynamic response of soil moisture and determining, based on eitherirrigation events or rainfall, the field capacity. This would be allowedto change over time (with some characteristic time constant—probably onthe order of ten days) to reflect changes in root mass, organic content,and soil compaction.

One aspect of the present invention is or more soil moisture sensors incommunication (wireless, wired, or otherwise) with a uC based “decisionelement.

Another aspect of the present invention is decision element with, orwithout, the capability to control/schedule irrigation over areas inwhich the communicating sensors are installed.

Yet another aspect of the present invention is uC based algorithms thatinterpret soil moisture data and automatically produce measurements offield capacity or other appropriate measures of a soils response toirrigation.

Yet another aspect of the present invention is in systems that allow thedecision element to control irrigation, the irrigation would beautomatically set based on the determined field capacity.

Having briefly described the present invention, the above and furtherobjects, features and advantages thereof will be recognized by thoseskilled in the pertinent art from the following detailed description ofthe invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a top perspective view of a wireless soil sensor of thepresent invention with a sleeve attached over a portion of the wirelesssoil sensor.

FIG. 2 is a first side view of the wireless soil sensor of FIG. 1.

FIG. 3 is an opposing side view of the wireless soil sensor of FIG. 1.

FIG. 4 is top plan view of the wireless soil sensor of FIG. 1.

FIG. 5 is a top perspective view of a wireless soil sensor of thepresent invention without a sleeve attached over a portion of thewireless soil sensor.

FIG. 6 is a first side view of the wireless soil sensor of FIG. 5.

FIG. 7 is top plan view of the wireless soil sensor of FIG. 5.

FIG. 8 is a rear plan view of the wireless soil sensor of FIG. 5.

FIG. 9 is a front view of an interrupter with a front panel open.

FIG. 10 is a front view of an interrupter with a door closed.

FIG. 11 is a top perspective view of an interrupter with a front panelopen to illustrate an interface.

FIG. 12 is a top perspective view of an interrupter with a front panelclosed.

FIG. 13 is an isolated view of an interface of an interrupter.

FIG. 14 is a flow chart of a general method of an end-to-end system ofthe present invention.

FIG. 15 is a schematic diagram of a prior art irrigation control system.

FIG. 16 is a schematic diagram of an irrigation control system with anirrigation interrupt.

FIG. 17 is a schematic diagram of an irrigation control system with awireless irrigation controller.

FIG. 18 is a schematic diagram of a prior art irrigation control system.

FIG. 19 is a schematic diagram of an irrigation control system with atethered sensor.

FIG. 20 is a schematic diagram of an irrigation control system with awireless interrupt.

FIG. 21 is a schematic diagram of an irrigation control system with awireless controller.

FIG. 22 is a block diagram of a preferred embodiment of an irrigationinterrupter.

FIG. 23 a schematic diagram of an irrigation system employing aninterrupter of the present invention.

FIG. 24 a schematic diagram of an irrigation system employing aninterrupter of the present invention.

FIG. 25 is a block diagram of a preferred embodiment of a wirelesssub-surface soil sensor.

FIG. 26 is a graph.

FIG. 27 is a graph.

DETAILED DESCRIPTION OF THE INVENTION

The present invention may be used with a system and method such asdisclosed in Glancy et al., U.S. patent application Ser. No. 12/983,241,filed on Dec. 31, 2010 for an Apparatus And Method For Wireless RealTime Measurement And Control Of Soil And Turf Conditions, which ishereby incorporated by reference in its entirety.

The present invention may be used with a system, sensor and method suchas disclosed in Campbell, U.S. Pat. No. 7,482,820 for a Sensor ForMeasuring Moisture And Salinity, which is hereby incorporated byreference in its entirety.

The present invention may use a chemical sensor probe such as disclosein U.S. Pat. No. 4,059,499 which is hereby incorporated by reference inits entirety.

The present invention may use a chemical sensor probe such as disclosein U.S. Pat. No. 5,033,397 which is hereby incorporated by reference inits entirety.

The present invention may utilize the systems and methods disclosed inMagro et al., U.S. patent application Ser. No. 12/697,226, filed on Jan.30, 2010, for a Method And System For Monitoring Soil And WaterResources, which is hereby incorporated by reference in its entirety.

The present invention may also utilize the systems and methods disclosedin Magro et al., U.S. patent application Ser. No. 12/911,720, filed onOct. 25, 2010 for a Method For Soil Analysis, which is herebyincorporated by reference in its entirety.

Magro et al., U.S. patent application Ser. No. 12/698,176, filed on Feb.2, 2010 for a Method And System For Monitoring Soil And Water Resourcesis hereby incorporated by reference in its entirety.

Campbell et al., U.S. patent application Ser. No. 12/698,138, filed onFeb. 1, 2010 for a Method, System And Sensor For Performing SoilMeasurements is hereby incorporated by reference in its entirety.

Campbell et al., U.S. Pat. No. 8,035,403 for a Wireless Soil SensorUtilizing A RF Frequency For Performing Soil Moisture Measurements ishereby incorporated by reference in its entirety.

Campbell et al., U.S. patent application Ser. No. 12/697,258, filed onJan. 31, 2010 for a Method And System For Improving A CommunicationRange And Reliability Of A Soil Sensor Antenna is hereby incorporated byreference in its entirety.

Campbell et al., U.S. patent application Ser. No. 12/697,264, filed onJan. 31, 2010 for an Antenna Circuit Matching The Soil Conditions ishereby incorporated by reference in its entirety.

Campbell et al., U.S. patent application Ser. No. 12/697,283, filed onJan. 31, 2010 for an Adaptive Irrigation Control is hereby incorporatedby reference in its entirety.

Campbell et al., U.S. patent application Ser. No. 12/697,281, filed onJan. 31, 2010 for an Irrigation Interrupter is hereby incorporated byreference in its entirety.

Campbell et al., U.S. patent application Ser. No. 12/697,292, filed onJan. 31, 2010 for a Wireless Soil Sensor Utilizing A RF Frequency ForPerforming Soil Moisture Measurements is hereby incorporated byreference in its entirety.

Campbell et al., U.S. patent application Ser. No. 12/697,256, filed onJan. 31, 2010 for a Method And System For Soil And Water Resources ishereby incorporated by reference in its entirety.

Campbell et al., U.S. patent application Ser. No. 12/697,257, filed onJan. 31, 2010 for a Method And System For Soil And Water Resources ishereby incorporated by reference in its entirety.

Systems, methods, sensors, controllers and interrupters for optimizingirrigation are disclosed in Campbell et al., U.S. patent applicationSer. No. 12/697,258, filed on Jan. 31, 2010, for a Method And System ForImproving A Communication Range And Reliability Of A Soil SensorAntenna, which is hereby incorporated by reference in its entirety.

Likewise, systems, methods, sensors, controllers and interrupters foroptimizing irrigation are disclosed in Campbell et al., U.S. patentapplication Ser. No. 12/697,254, filed on Jan. 31, 2010, for a MethodAnd System For Soil And Water Resources, which is hereby incorporated byreference in its entirety.

Magro et al., U.S. patent application Ser. No. 13/017,538, filed on Jan.31, 2011 for an Automatic Efficient Irrigation Threshold Setting ishereby incorporated by reference in its entirety.

A wireless soil sensor 21 is shown in FIGS. 1-8. The wireless soilsensor is placed in the soil below the surface to monitor variousparameters of the soil such as moisture. Other parameters includesalinity and temperature.

A wireless interrupter 12 is shown in FIGS. 9-12 and an interface 12 forthe wireless interrupter 12 is shown in FIG. 13. The wirelessinterrupter 12 has a main body 12 a and a front panel 12 b which allowsfor viewing of the interface 12 c.

As shown in FIGS. 23 and 24, an irrigation system employing aninterrupter 12 is generally designated 20. The system 20 preferablyincludes a plurality of wireless sub-surface sensors 21 (upper soil 21 aand lower soil 21 b), a plurality of above-ground receivers 22, aninterrupter 12 located at an operations center, and a plurality ofabove-ground sensors 24. The above ground sensors 24 preferably measuresair temperature, wind speed, and relative humidity.

FIG. 22 illustrates a block diagram of the preferred components of aninterrupter 12. The interrupter 12 preferably has a housing 70, amicrocontroller 71, a radiofrequency antenna 72, a memory 79, a display73 and a power supply 74.

FIG. 25 illustrates a wireless sub-surface sensor 21 alternativelyutilized in the system 20. The wireless sub-surface sensor 21 preferablyhas a housing 30, a processor 31 with an integrated sensor 33, aconfiguration switchable antenna 32, and a power supply 34.

A schematic diagram of a prior art irrigation control system is shown inFIG. 15.

A wireless device (soil sensor 21, interrupter 12 or controller 11)typically goes through a network entry process, in which it searches forand locks onto the signals of other members of the wireless network itis entering. After the signal lock, a handshake takes place, where theentering node transmits and expects to receive a sequence of welldefined messages over the air. At the conclusion of this handshake, theentering node is considered a member of the network. It will be able totransmit and receive over the air messages using a well definedprotocol. It will be considered a “Joined” member. A “joined” member maymaintain a connection oriented or a connection less link with its radioneighbors. (Example of a connection oriented link is a time synchronizedCDMA channel between a station and a cell tower. Example of aconnection-less link is the Carrier Sense Medium Access (CSMA) linkbetween a WiFi station and its Access Point).

Typically, if the “joined” member is not able to communicate with theother end of the link within a predefined window, it loses its “joined”status, and has to go through a network entry process again. At theleast, it may have to perform a less complex re-synchronization task tore-establish its time synch with the network (if is uses a connectionoriented link). The link establishment, re-synch, or network entryprocess will continue (typically with less and less frequency, uponfailed attempts) until a) the node rejoins the network, b) the timeinterval between reentry attempts becomes so large that the nodeeffectively becomes dormant, or c) until the node runs out of battery.

The wireless soil sensor 21 is required to transmit messages for all ofthe above transactions. If the cause of loss of “joined” status is duesto surrounding soil that is too moist or too saline then the rejoinattempts will also fail. If this condition is not detected, the wirelesssoil sensor 21 will continue wasting scarce battery reserves fortransmissions. The adaptive transmission scheduling mechanism discussedhere takes into account the moisture and conductivity of the soil thatsurrounds the wireless soil sensor 21. It will stop transmissions untilthe moisture levels of the soil surrounding the node have dropped tomanageable levels that will allow successful transmissions.

An example of a preferred method of adaptive transmission for wirelesssoil sensor 21 is as follows. A preferred method for an adaptivetransmission aspect of the present invention begins with determining if(x) number of consecutive connection attempts (or transmission) havefailed. Next, the method includes determining if the measured moisturelevel (or a composite metric that includes moisture and conductivitylevels) is at some threshold (y) or above. Next, the method includesassuming the surrounding soil is too wet. Next, the method includessuspending the timers that control the transmission activity of thenode. Next, the method includes, continuing to sample the moisturelevels, and as long as the moisture levels are above threshold (z),attempting to connect once every predetermined time period, T (T timeunits only, where T is larger than typical inter-transmissionintervals). Next, the method includes determining when the moisturelevels have dropped below a threshold (w), then un-suspending the timersand a state machine that controls transmissions. Next, the methodincludes, allowing the normal protocol to resume for the system.

One can manage what one can measure. And, one can do it all on a realtime basis. Soil intelligence equals savings and health. The presentinvention is preferably a complete package of advanced software,agronomic services and wireless sensor system that helps take theguesswork out of turf management. A flow chart of an overall method isshown in FIG. 14. On aspect of the present invention turns raw data intouseful operating thresholds which help maintain and optimize planthealth and performance. One aspect of the present invention provides thenecessary formula that automatically alerts when and where a facilitymight be experiencing stress and what the treatment options are.

One aspect of the present invention has a data collection component ofthe software, which allows for monitoring in real time, from an officeor from on-site or remote locations, the key variables of moisture,salinity and temperature from each sensor site. The graphic displays areuser-friendly and the present invention helps set high-low thresholdranges for each sensor location so that one instantly knows whether thesoil is in or out of the optimal range for growth conditions andplayability. By continuously analyzing the recorded data and thresholdsfor each location, this component visually alerts one to conditions ateach sensor location and suggests what actions are needed to be moreefficient and effective.

One aspect of the present invention optimizes turf and crop health andplayability by measuring root zone moisture, salinity and temperatureand applying best practices to your turf management. Once the wirelesssoil sensors 21 are in the ground sending raw data, an optimal zone isdevised by analyzing accumulated sensor data, putting decades ofagronomic experience to use and applying tested scientific principles.The Zone defines the upper and lower operating thresholds to ensureplant health. This helps with: course evaluation; soil and wateranalyses; review of existing practices including irrigation, nutritionalinputs and maintenance; threshold determinations; sensor placement andmore. On a real-time basis, one can manage greens, tees, fairways andrough to keep a facility in prime condition.

The wireless soil sensor 21 provides wireless interface between thesensing elements and the Communication Control Nodes (CCNs) thatpreferably form a mesh network. The key features include the shape: 8×4inches. Buried with a Standard Cup Cutter. Supports sensors: analog ordigital. 3 “D” Cell batteries: 4+ years life, field replaceable. 1 WattFHSS radio board supports approximately 400 ft. range 4 in. in ground.Sensor interface and antenna for over air programming for productupgrades.

The key functionalities of the wireless soil sensor 21 are as follows:provide accurate, real-time data on soil moisture, temperature andsalinity. Key Features: Pre calibrated for sand, silt and clay. Moisturemeasurement. Accuracy: +/−0.02WFV from 0 to saturation at <2.5 dS/mconductivity. +/−0.04WFV from 0 to saturation at 2.5-5 dS/mconductivity. Repeatability: +/−0.001WFV. WFV is the fraction of soiloccupied by water, a soil at 10% soil moisture has a WFV of 0.10.Conductivity measurement: Accuracy: +/−2% or 0.02 dS/m, whichever isgreater, 0-2.5 dS/m. +/−5%, 2.5-5 dS/m. Repeatability: +/−1% or 0.01dS/m whichever is greater, 0-2.5 dS/m. +/−4%, 2.5-5 dS/m. Temperaturemeasurement: Accuracy: +/−0.5° C. from −10 to +50° C., +/−1° F. from 14to 122° F. Repeatability: 0.05° C., 0.1° F. Benefits: Dual sensors allowgradients of soil moisture, conductivity, and temperature to bemonitored. High accuracy and repeatability. No individual sensorcalibration required.

Above-Ground Wireless Mesh Network: Communication Control Nodes. KeyFunctionality: CCNs are the interface to the Sensor Nodes. Each is aradio node that automatically joins and forms the mesh network on powerup. Key Features: Range of ˜1 mile above ground unobstructed. Requires 1Amp while transmitting. 12-24 Volt AC or DC power. Can be attached via110/220 Volt power adapter. Weather proof enclosure. Benefits: Selfforming, self healing, multihop mesh network; No special wiringrequired; Two way communications with link quality statistics; Controlof buried nodes; The multihop mesh allows extension of the wirelesscoverage area far beyond the nominal range of the radios.

Agronomy is the study of plant and soil sciences and how they impactcrop and plant production, performance and yield. Every plant hasspecific tolerances to environmental variables like moisture,temperature and salinity which impact the ability to grow, flourish,proliferate and perform to expectations. Just as a doctor can helpmonitor and advise to keep a person in peak physical condition,agronomists can help keep your facility in peak condition. Agronomistsusing the present invention help define those optimal threshold levelsas well as their impacts on root, leaf and lateral growth, responses toman-made or natural environmental stress, and resistance to disease andinsect pressure. As a result, in this case water usage was reduced bynearly 30% while playability was enhanced uniformly. The indicator ofthe present invention predicts the likelihood for disease outbreaksbefore they happen.

The software package utilized feeds off data provided by the wirelesssoil sensors 21 and wireless communications system. It displays realtime conditions and provides comprehensive intelligence and predictiveactions. The system helps establish health- and performance-optimizingoperating threshold ranges, evaluate your data and current practices,and refine existing programs. The results, optimal turf conditions andreal savings, will generate a strong and lasting return on investment.The agronomic benefits include more efficient salinity management,uniform irrigation, deeper rooting, predictive disease control andhealthier, more stable conditions. There are environmental benefits aswell like water conservation, reduced use of phosphates, nitrates andpesticides, a reduced carbon/water footprint and regulatory compliance.

Real time sensor measurements can include soil oxygen, pH,concentrations of specific ion species—(Na+ has a very detrimentaleffect compared to the same concentration of Ca+2). Pollutantmeasurements include both hydrocarbons (oils, gasoline, etc.) and metals(chromium, lead, etc.).

As to the wireless transmission network, an alternative process of anadaptive model may be utilized with the present invention. An antenna,designed for efficient RF communication in air is relativelystraightforward because the key electrical properties of thetransmission medium (air) are well known and essentially constant. Inbelow ground RF transmission, the key properties of the soils will verygreatly with moisture content and salinity hence it is a much moredifficult problem to design an efficient antenna. In addition, the bestantenna design is influenced by how deeply buried the antenna is. Thepresent invention includes elements to the antenna circuit that, undercontrol of microcontroller, allow for varying the properties of theantenna to more closely match the conditions and improve range andreliability of communication. The sensor of the present inventionmeasures both the dielectric constant of the soil (moisture) andconductivity (salinity) directly. Hence, the sensor measures preciselythe two most important factors affecting antenna efficiency.

In a predictive model, the method includes activating a sensor andmeasuring soil electrical properties. The method also includes, based onthe soil properties, activating antenna elements to give an effectivetransmission. The method also includes transmitting sensor data.

In an adaptive model, the method includes activating a sensor andmeasuring soil electrical properties. The method also includestransmitting data repeatedly until all switchable antenna configurationshave been attempted. The method also includes monitoring signal strengthfor each transmission. The method also includes repeat this processpossibly every 60 sensor transmissions.

As time progress, a receiver can put together a two dimensional map(soil dielectric constant on one axis, soil conductivity on the other)with received power for all antenna configurations. The map isdownloaded on some regular schedule to the buried sensor node. When thesensor makes a measurement, the sensor reviews the map for the antennaconfiguration that gives the highest receive power at the receiver forthe current conditions. A node configures an antenna and sends a packetof data. Even after the map is downloaded, every 60 sensor readings willhave all the different antenna configurations attempted which will allowthe map evolve.

The advantage of this adaptive process is that it can make an allowancefor the actual depth of burial as well as the relative antenna locationsand orientations. This is important because different antennaconfigurations have different radiation patterns. Hence, it is possiblethat a less than ideal antenna configuration works best in that it hasthe highest radiated power in the particular direction and polarizationthat the receiver antenna lies in.

As shown in FIG. 15, an irrigation system 10′ includes a 24VAC powersupply, a controller 11, and a valve box 13 with valves 123 a and 13 b.These irrigation systems 10′ work by using a 24 volt alternating currentsource to open valves 13 a and 13 b. When no current flows (open switch51), the valves 13 a and 13 b are closed and no water flows. Acontroller/timer 11 is used to turn on the current to the separatevalves 13 a and 13 b. Usually there is a “common” wire 53 that returnsthe current from all valves 13 a and 13 b. Separate “hot” wires 52 a and52 b are used for each of the valves 13 a and 13 b. As shown in FIG. 18,the irrigation controller 11 controls the valve box 13 through wires 17a and 17 b to provide water form source pipe 16 b to sprinkler pipe 16 afor dispersion on a soil 15 through sprinkler 14.

As shown in FIG. 19, the prior art is improved upon by a system 10 witha tethered sensor 21′ in which is a sensor coupled to an interrupter 12wired into the wiring 17 a, 17 b, 17 c and 17 d of the valve box 13. Theinterrupter 12 acts to turn off a scheduled irrigation if the moistureexceeds a predetermined threshold established by a user. The interrupter12 acts as an in-line switch that closes (allowing current to flow andthe valve 13 to open) only if the controller 11 starts a scheduledirrigation and the soil moisture is below a predetermined thresholdestablished by a user). In the system 10 of FIG. 19, the interrupter 12can only interrupt a scheduled irrigation, not initiate an irrigation.The system 10 has a sensor 21 which is cabled (no wirelesscommunication). The system 10 of FIG. 19 has the advantage of being verysimple, it is capable of being easily installed into virtually allexisting irrigation systems, and it requires no independent power (thesystem 10 draws power off the 24VAC irrigation line).

As shown in FIG. 20, a wireless interrupt approach is similar to the“Tethered Sensor” system 10 of FIG. 19, except that wirelesscommunication is used between a wireless soil sensor 21 and aninterrupter 12. The wireless soil sensor 21 requires battery power andthe interrupter 12 requires a battery to accommodate flexible wirelessreporting. The principle advantage of the system 10 of FIG. 20 is thatno cabling is needed, and installation is simpler than the tetheredsystem 10 of FIG. 19. As shown in FIG. 20, the wireless soil sensor 21transmits a wireless signal 18 a to the interrupter 12 pertaining to themoisture levels of the soil in a particular soil area.

A wireless controller system 10 is shown in FIG. 21. The wirelesscontroller system 10 uses a wireless link back to a wireless irrigationcontroller 11 (there is no “interrupter”) The principle advantage of thewireless controller system 10 of FIG. 21 is that the wireless soilsensors 21 preferably initiate irrigation if needed (allowing for theuser to set scheduled irrigation times as well if desired). A user alsomay allow the wireless controller 11 to look at more than one wirelesssoil sensor 21 for each irrigation zone (area irrigated by one valve 13)taking an average, use the lowest value, etc. One can also allow forsimpler level adjusting, including such features as a “hot day” buttonnudging the target water levels up a notch and many others.

The goal of one aspect of the present invention is to develop aninexpensive and easy to install system compatible with existingirrigation systems that can be quickly configured byhomeowners/landscapers of limited technical sophistication. An objectiveof the present invention is an overall lower cost, a system that is easyto install in existing and new irrigation systems, setup that is as easyto use as a traditional irrigation controller, and careful design ofsetup features, default modes, user input device and display to give asuperior customer interface.

Irrigation interrupt of the system interfaces simply with existingirrigation control systems to over-ride scheduled irrigation whenmoisture levels hit user settable thresholds. When operating in thismanner, the system is incapable of initiating an irrigation event andneeds to be used with a conventional irrigation controller. Anirrigation controller 11 of the system 10 can initiate and stopirrigation events and replaces existing installation irrigationcontrollers or is suitable for complete control of new installationsthrough both timing of irrigation to certain times of the day as well asbased on near real-time soil moisture data.

As mentioned above, a typical irrigation controller system 10′ is shownin FIG. 15. The system 10′ includes a 24VAC power supply connected to120VAC and an irrigation controller 11. Wiring 52 a and 52 b leads fromthe controller 11 to one or more valve boxes 13. When the current loopis closed, the valves 13 a and 13 b open and a zone is watered.Typically, the controller 11 is set to turn on and off valves atpredetermined times for a set time.

In the irrigation interrupt system 10, as shown in FIG. 16, theinterrupter 12 is positioned between the standard irrigation controller11 and the valves 13 a and 13 b. A wireless soil sensor 21 is placed ineach irrigation zone and the wireless soil sensor 21 is in periodiccommunication with the irrigation controller 12. In this system,watering only occurs when both the standard irrigation controller 11indicates that it is time to water and the irrigation interrupter 12indicates that soil moisture is below a predetermined threshold. Theinterrupter 12 opens switch 54 a and 54 b to terminate the current flowthrough lines 52 a′ and 52 b′ and close the valves 13 a and 13 b. Line55 provides power to the interrupter 12, especially when the switch 51of the controller 11 is open.

In the wireless irrigation controller system 10 of FIG. 17, the sameinterrupter hardware is used but the inputs to the irrigationinterrupter 12 are always on, i.e. the irrigation interrupt 12 is now incontrol and irrigation will occur under the direct control of thewireless interrupter 12 based on soil moisture data. Different firmwareis necessary, but the hardware is identical with only minimal changes inthe wiring.

In both systems, power for the irrigation interrupter 12 is drawndirectly off the 24VAC eliminating the need for a separate power supply.

The system 10 is capable of operating with soil moisture only wirelesssoil sensors 21 with integrated two-way wireless telemetry, sensorfirmware, an irrigation interrupter/controller (Controller) andcontroller firmware. The wireless soil sensors consist of a soilmoisture only sensor, wireless two-way telemetry, microcontroller, andat least some non-volatile memory, and are preferably battery powered.These components are integrated into one physical package (no cabling)and the wireless soil sensor 21 is buried in strategic locations tomonitor soil moisture conditions. The sensor firmware manages makingsensor measurements, transmitting them to the controller, receivingcontroller commands, and power-management (putting system to sleep). Thecontroller 11 preferably consists of two-way wireless telemetrycompatible with the wireless soil sensors 21, a microcontroller,non-volatile memory, a user input (preferably a four or five way wheel),display (preferably 36 character two line LCD), and circuitry foropening or closing switches for irrigation zones (switch in an openposition is over-riding irrigation). In existing irrigation systems andfor use with an already installed controller, the wireless controller 11is spliced into existing wiring close to an existing irrigationcontroller. In replacing an existing irrigation controller or in newinstallations, the wireless controller 11 is directly connected toirrigation zone wiring. The controller firmware allows collection ofwireless telemetry of soil moisture data, “commissioning” of newwireless soil sensors 21, i.e. associating a wireless soil sensor 21with an irrigation zone and an installation, setting irrigationthresholds, etc.

All of the components preferably operate over a temperature range of −20to 70° C. (with the exception of the display which is operable over 0 to50° C.) and are capable of storage over −20 to 70° C. All componentspreferably are Human Body Model ESD resistant but not lightningresistant. Wireless soil sensors 21 are preferably fully waterproofwhile the interrupters 12 preferably only have a low level of“splashproofing”. For the purposes of determining battery shelf life inthe wireless soil sensors 21, a temperature under 40 C is assumed(temperature, depending on battery technology, can greatly impact selfdischarge rates).

Wireless telemetry range of approximately 100-200 feet is preferred. Therange is achieved at depths of up to 12 inches and in moderate clutter(vegetation, slight topography, through garage wall, etc.). A wirelesssoil sensor 21 is preferably installed at least as close as 3 inchesfrom soil surface for monitoring soil moisture in shallow rooting turf.The package of the wireless soil sensor is preferably no larger than2″×2″×8″ (ideally 1.5″×1.5″×6″). A bulky package is difficult to install(particularly at shallow depths), disrupt soil environment, and aturn-off to consumers. A non-volatile memory is preferred. Timekeepingis accurate to within +/−2% which allows the wireless soil sensors 21 towakeup at on a regular schedule, timing for I2C commands, as well asscheduling sensor “listen” windows for wireless receive modes.

The wireless soil sensor 21 is capable of receiving simple operationalparameters wirelessly from a controller 11 or an interrupter 12, whichallows the controller 11 or the interrupter 12 to set reportinginterval, selection of adaptive algorithms, etc.

A procedure for re-programming the wireless soil sensors 21 afterproduction is included in order to allow for changes encountered indebugging or upgrades. Alternatively, it can be through a programmingheader in the battery or by some other wireless programming option.

The wireless soil sensor 21 is preferably able to detect imminentbattery, to prevent the wireless soil sensors 21 from failing suddenlywith no warning or begin to operate intermittently reflecting batterytemperature and other variable as well as possibly giving corrupted datathat may result in incorrect irrigation decisions.

The sensor firmware is capable of executing and reading I2C commands.Analog sensor requires I2C commands to control oscillator and make A/Dmeasurements. I2C commands need to be executed sequentially according toa sloppy timing of about +/−3 mS over 100 mS. I2C can operate anywherefrom 20 to 200 KHz. The sensor firmware is able to perform simplecalculations like conversion of raw A/D values into soil moisture whichrequires simple functions-addition, subtraction, division, polynomialsbut no log, trig, etc. functions. The sensor firmware is capable ofgoing into a very low power mode between set measurement interval withroutines to wake up at end of interval which may range from 1-100 min.which is set in a non-volatile configuration file which can be modifiedby interrupt controller. After measurement is complete, soil moisturedata needs to be sent to interrupt controller 11.

The sensor firmware preferably has a static soil moisture mode. Anoperational mode that allows the wireless soil sensor 21 to wake up,measure soil moisture, and if a change in soil moisture from the lastwirelessly reported measurement does not exceed a settable threshold,return to a sleep mode without sending data. This threshold value, aswell as whether this feature is enabled, preferably resides in anon-volatile configuration file which can be modified by the interruptcontroller 11. The wireless soil sensor 21 preferably transmits a newreading once every six hours regardless of soil moisture changes toconfirm operation.

The wireless soil sensor 21 preferably has a default mode firmware uponpower restart for the sensor firmware, which allows a wireless soilsensor 21 to be commissioned, i.e. assigned to a specific irrigationinterrupter to allow for resolving sensors from a close neighborsresidence. In addition, commissioning must be flexible to allow for achange in assigned interrupt controller 11 in the future or ifcommissioning is lost.

A wireless soil sensor 21 is preferably capable of a listening mode in apower efficient manner for receiving changes to the configuration filewirelessly from the interrupt controller 11 with a maximum file size of100 bytes at least once a month without degrading three year sensorbattery life. The wireless soil sensor 21 preferably has the ability todownload full operating firmware.

On a regular schedule (about once every six hours) the wireless soilsensor 21 preferably provides in addition to the soil moisture value,diagnostics such as battery voltage, and raw measured values not toexceed an additional 25 bytes. This data is used to assess performanceand for diagnosis of bugs or sensor failure.

If the raw A/D values used to determine soil moisture data are out ofnormal ranges, the wireless soil sensor 21 preferably sends a “Bad Data”even if the computed soil moisture value appears reasonable. This helpsdetect failed wireless soil sensors 21 and prevent bad control actions.

The irrigation interrupter 12 is capable of turning on and off ACcurrent up to 700 mA continuously at 70 C for each irrigation zone froman AC voltage range of 16 to 34 volts with no more that 1V in dropacross switching circuitry. Switching circuitry is not damaged byinductive transients generated by the turn off of valve solenoids.

Regardless of whether the interrupt controller 11 is allowing orblocking irrigation, the interrupt controller 11 can detect the presenceof an AC voltage (generated by irrigation controller 11 to initiate anirrigation). This feature allows for calculations of savings such as %of scheduled irrigation events that were canceled by system.

The hardware for the irrigation interrupter 12 is preferably resistantto moderate ESD and transients that may enter system through 24 VACtransformer in order to be reliable.

The interrupt controller 11 draws power directly from nominal 24VACtransformer to avoid having to use a separate power supply with amaximum current draw of 100 mA. The interrupt controller 11 operatescorrectly with an AC input varying from 16 to 34 VAC to account for ACmains voltage of 84 to 130 VAC (typical specified level of AC power seenin a household) and variation in transformer output with load.

The interrupt controller 11 is capable of operating in typicalresidential systems which have between four and eight zones. Moresophisticated systems could be addressed by using multiple units.

The interrupt controller 11 is preferably capable of a log for the last30 days of soil moisture readings for eight zones at 10 minute intervalas well as whether an irrigation event is occurring, and whether it hasbeen interrupted at 1 minute intervals in non-volatile memory. The logis preferably structured so accurate date and time is available for datarecord. This feature is good for both debugging purposes but also inallowing the system to display to the user the amount of water savedthus justifying the product.

Firmware responds as gracefully as possible to problems. For instance,if soil moisture data is out of range or uC lockup (possibly detected bywatchdog circuit) irrigation proceeds according to the irrigationcontroller 11 (i.e. no interrupt). If an irrigation interrupter 12 isoperating as a wireless irrigation controller (no standard irrigationcontroller), the system 10 should default to no irrigation. Failuremodes give obvious indication of problems.

Ample code space is preferably reserved to allow for extensiveadditional features in the future. All user settable configurations arepreferably stored in non-volatile memory so as to allow for seamlessrecovery from lockup or loss of power. Preferably, a real time clock hasthe ability to keep time after power loss for up to 1 month.

The interrupter firmware is capable of generating a user water savingsreport for the last day, week, and month (i.e. percent of scheduledirrigation that was interrupted) by zone and as a whole for all eightzones as well as total run time per zone.

A process is developed to allow sensors upon installation or systemexpansion to be assigned to a particular irrigation zone for aparticular irrigation interrupter. The process needs to be flexibleenough to allow for replacement of failed wireless soil sensors 21 aswell. This allows the system 10 to be used with neighboringinstallations without confusion as well as assigning the right sensor tothe right zone.

A user sets, for each zone, the maximum soil moisture level that willterminate an irrigation event. There is also a settable hysteresis, Y,i.e. if during a single scheduled irrigation event the soil moisturerises about the threshold X and irrigation is stopped, it would notbegin again until level fell to X-Y. This prevents valves from turningon and off rapidly when approaching the threshold. When new irrigationevent occurs, the threshold defaults back to X.

A hold feature allows a user to hold current conditions going forward(i.e. take last soil moisture readings and apply as thresholds).

A show current status mode for the interrupt controller 11 defaults towhen no keypad entry has occurred for a minute or so and shows zone byzone-threshold, last soil moisture data, irrigation is being attempted,and if irrigation is being interrupted.

The save configuration allows up to six configurations to be saved,named, and recalled (for all zones thresholds, hysteresis, adaptivealgorithms on or off, etc.). This allows for summer and winter settings,etc.

A disable setting is where all zones are enabled and the system is undercontrol of the irrigation controller 11 solely, i.e the interrupter 12allows valves 13 a and 13 b to be on at all times when the standardirrigation controller 11 schedules irrigation regardless of the soilmoisture data. This is a “safety mode” so that if there are criticalproblems, the user is not forced to reconfigure things to keep the grassfrom dying.

A bump feature allows a user to “bump” up or down all thresholds equallyat an approximately 0.5% water by volume increment (allows for quickadjustment for hot weather or other reasons), which revert to previoussettings after 1 days unless user selects to apply them permanently.

The firmware is preferably capable of detecting missing or out of rangesoil moisture and low battery conditions and display warning.

A wireless irrigation controller mode allows the irrigation interrupter12 to function as full soil moisture data driven irrigation controller11 without the use of a standard irrigation controller 11. Essentiallyall of the features of a standard irrigation controller 11 areimplemented such as scheduling irrigation times, valve run-times, etc.These scheduled events are subjected to the same “interrupt” schemes asthe irrigation interrupter 12 based on soil moisture data.

When water is applied to the soil the wireless soil sensors 21 reportthe increase in moisture content but also look at the tail off inmoisture levels when irrigation ceases. In cases of significantoverwatering, there is a sharp spike in moisture levels followed by asharp fall after irrigation ceases. This is due to the soil essentiallybeing so wet it “free drains” below the root zone (thus wasting thewater). The present invention implements algorithms to monitor this andadjust irrigation events to eliminate this wasteful practice allowingthe system to essentially configure itself over time. The wireless soilsensor 21 is preferably directly integrated with a radio andmicrocontroller. It also preferably has a sleeve that fits over thesensor that the user removes to turn it on. It also preferably has anoptional microcontroller generated clock signal to avoid having to use aseparate oscillator for the conductivity measurement. It also preferablyhas the same RF frequency the radio uses to eliminate having to use aseparate oscillator for the soil moisture measurement. It alsopreferably uses “spread spectrum oscillators” to achieve FCC compliance.It also preferably has sensor components that are currently PCB may bemade out of conducting plastic formulations simplifying assembly,improving aesthetics, and reducing costs.

In FIG. 26, the soil moisture value shows three peaks corresponding toirrigation events. The initial big spike up was caused by dumping wateron the sensor install site shortly after installation (this was doneintentionally). It shows a number of classic features of rapid run-up insoil moisture following irrigation, a quick fall as water rapidlypercolates to depth (most likely due to exceeding field capacity). Ascaled soil moisture gradient (it is essentially the derivative of soilmoisture as a function of time—the slope of the curve) is also shown. Itis scaled to fit on the same graph and the signs are switched so that apositive value reflects a declining soil moisture. All of the negativevalues (rising soil moisture) are suppressed as they are not useful inthe proposed scheme.

In FIG. 27, the soil moisture gradient is plotted as a function of soilmoisture.

The theoretical basis of this approach is that the higher the soilmoisture value, the greater the hydraulic conductivity is. Hydraulicconductivity measures how fast a gradient in the soil moisture isremoved by moisture flowing from the wet to dry areas. Hydraulicconductivity is highly soil dependent and can increase by orders ofmagnitude from dry to wet. When field capacity is reached, hydraulicconductivity becomes very high (flow rate is then limited by the abilityof water to flow to depth and is high for a sand and much lower in aclay).

This is roughly borne out in the graph above. The data clusters belowthe line called the static threshold are at about a SM gradient of 3. Ofimportance is that the resolution in the saved moisture data (0.1%)results in a SM gradient of 0.5 (this is an approximate noise floor inthat rounding errors could cause a value of 0.5). In addition, if amoderate 0.3″ of ET is occurring over a 10 hour period in a soil withturf roots to 6″ we would expect a SM gradient (caused by the turfextracting water of about 1. Obviously, in some cases the ET will behigher and may occur over a shorter time, water will be preferentiallyextracted near our sensor depth, etc. Hence, a limit of 3 is set as asoil moisture gradient under relatively static conditions where moistureisn't percolating below the root zone. The idea is that the intersectionpoint shown in the graph represents a point where we should expectlittle percolation of soil moisture below the root zone.

It is important to make sure the data entering the algorithm is free ofanomalies (wild soil moisture values caused by corrupted packets),missing data points, data right after the irrigation event ends, etc.

Calculation of First Derivative is a simple process of subtracting datapoints to get rate of change. Negative values (wetting events) arerejected.

Lumping all soil moisture gradient values for particular windows (0-1%,1-2%, . . . 69-70% soil moisture) allows application of adaptivealgorithms that allow for water thresholds to adapt over time as newdata comes available (for example, keep 90% of old value, 10% of mostrecent value giving the possibility of a slow drift with time). It willalso allow for noise reduction by schemes such as tossing out the valuesabove or below one standard deviation from the bucket average.

Curve Fitting/Statistical Analysis determines “Static Threshold” orassumes a value, and fits data points above static threshold anddetermine intercept point. This would be the upper end of the irrigationtarget.

From the foregoing it is believed that those skilled in the pertinentart will recognize the meritorious advancement of this invention andwill readily understand that while the present invention has beendescribed in association with a preferred embodiment thereof, and otherembodiments illustrated in the accompanying drawings, numerous changesmodification and substitutions of equivalents may be made thereinwithout departing from the spirit and scope of this invention which isintended to be unlimited by the foregoing except as may appear in thefollowing appended claim. Therefore, the embodiments of the invention inwhich an exclusive property or privilege is claimed are defined in thefollowing appended claims.

We claim as our invention:
 1. A method for automatic irrigationthreshold setting, the method comprising: measuring a dynamic responseof soil moisture of a soil area under a fully saturated environment;deducing at least one of a plurality of soil/landscape propertiescomprising field capacity, water infiltration rates, presence of thickorganic surface areas; producing at least one of a plurality ofrecommendations for management practices comprising aeration, thatchremoval, soil amendment; detecting at least one of a plurality ofirrigation system deficiencies comprising broken sprinkler heads, driplines, and poor spatial coverage; setting a threshold for the soil areabased on the measurements of the dynamic response; and monitoring thedynamic response of soil moisture over a predetermined time period;wherein measuring the dynamic response is performed by a systemcomprising a plurality of wireless sub-soil sensors, a smart irrigationcontroller in communication with each of the plurality of wirelesssub-soil sensors, wherein the smart irrigation controller comprises ahousing, a microcontroller, a radiofrequency antenna, a memory, adisplay and a power supply; wherein the smart irrigation controllersuspends scheduled watering if the soil moisture is above the threshold;wherein the smart irrigation controller continues monitoring the soilmoisture level to determine if the soil moisture level has dropped belowthe threshold; wherein the smart irrigation controller returns toscheduled watering once the soil moisture level is below the threshold;wherein the smart irrigation controller can only interrupt a scheduledwatering and not commence a scheduled watering.
 2. The method accordingto claim 1 further comprising monitoring an increase in soil moisture inresponse to a period of time of active irrigation to determineirrigation efficiency as well as to determine runoff and run timesrequired to account for soil moisture deficits during irrigation events.3. The method according to claim 1 wherein the threshold is 70% to 80%of the field capacity of the soil area.
 4. The method according to claim1 wherein the soil area is a residential lawn.
 5. The method accordingto claim 1 wherein the threshold is set to optimize water efficiency andplant growth add plant health, minimize runoff, and minimizecontamination to groundwater.
 6. The method according to claim 1 whereinthe soil area is at least one of a golf course, a farm, a footballfield, and all irrigated recreational surfaces, agricultural operations,gardens, landfill caps, and other land areas being restored to plantcovering.
 7. The method of claim 1 whereby all adaptive algorithmoperations are consistent with watering restrictions that are imposed byregulatory authorities or imposed by the end user to prohibit wateringduring certain times.